Protective electric coupling

ABSTRACT

Two complementary couplers, i.e., a socket and a plug, are provided with mating connectors whose interengagement completes a circuit connection between a supply line and a load, the connectors of the socket being normally made ineffectual or inaccessible by a safety mechanism which is deactivated only upon the approach of one or more magnets carried by the plug. The safety mechanism may include one or more blocking plates normally obstructing the socket connectors or a detent preventing manual displacement of conductive extensions of these connectors into engagement with coating supply terminals; in another embodiment, this mechanism comprises a circuit breaker which is moved by the approaching magnet or magnets to close both the main circuit and an ancillary circuit to energize a solenoid which intensifies the contact pressure between the connector extensions and the supply terminals, on the one hand, and respective bridge pieces on the circuit breaker.

United States Patent [191 Kersman ['11] 3,868,160 [4 1 Feb... 25, 1975 PROTECTIVE ELECTRIC COUPLING [22] Filed: Sept. 25, 1972 [21] Appl. No.: 292,163

[30] Foreign Application Priority Data Primary Examine'rDavid Smith, Jr. Attorney, Agent, or Firm-Karl F. Ross; Herbert Dubno I [57] ABSTRACT,

Two complementary couplers, i.e., a socket and a plug, are provided'with mating connectors whose interengagement completes a circuit connection between a supply line and a load, the connectors of the socket being normally made ineffectual or inaccessible by a safety mechanism which is deactivated only upon the approach of one or more magnets carried by the plug. The safety mechanism may include one or more blocking plates normally obstructing the socket connectors or a detent preventing manual displacement of conductive extensions of these connectors into engagement with coating supply terminals; in another embodiment, this mechanism comprises a circuit breaker which is moved by the approaching magnet or magnets to close both the main circuit and an ancillary circuit to energize a solenoid which intensities the contact pressure between the connector extensions and the supply terminals, on the one hand, and respective bridge pieces on the circuit breaker.

9 Claims, 13 Drawing Figures PATENTEUFEB25IQY5 3,868,160

' SHEET an 5 PATENTED FEBZS I975 snmxa'or 5 1 PROTECTIVEELECTRIC COUPLING BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective coupling for establishing an electric connection between two electric circuits, between two branches of an electric circuit, or between a power-supply network and an electric power-consuming device or load.

2. Description of the Prior Art The danger which surrounds household current-- outlet sockets is well known, not only tothose skilled in the electrical art, but also to the layman. Thisdanger becomes particularly evident when there are children around who, with their natural tendency to explore the unknown, attempt to insert extraneous objects, some of I which may be good electrical conductors, such as pins, needles, hair clips, scissors, etc., into the small holes which provide access to the contacts of the socket. The

consequences of such mischief are even better known ceived on the basis of different principles of operation. 7

However, most of such known arrangements are of a complex nature and therefore costly whereby the possibility of purchasing them is available only to a minority of the population in spite of the fact that the problem affects all income brackets.

I believe that other, simpler arrangements have also been conceived, such'as manually operated covers normally obstructing the socket, which must be rotated so as to permit ingress of the plug. This type of protector, although simple, has the disadvantage of being removable by hand and, therefore, not absolutely childproof.

The lack of widespread use of safety arrangements for rendering household sockets harmless, in spite of the danger involved, shows that there is a great necessity for providing a simple safety arrangement which overcomes the problems mentioned.

Although so far reference has only been made to the danger which is permanently present in houses, it will be evident to those skilled in the art that the same con siderations apply also in other fields of activity. In this respect it is often necessary to provide a male-female.

connector arrangement of a specific configuration vantages of the arrangements and devices known in the artQand which offers asolution to those problems that connection of two circuits, or two branches of a circuit.

It is an additional object of the present invention to provide a simple and cheap. protective coupling for both household and general use.

It is yet another object, of the present invention to y provide a household safety current-outlet socket which can be mounted in place of a conventional socket and which does not require any. preliminary modification of the box housing such conventional socket to adapt it to my improved socket. I

It is still a further object of the present invention to provide a safety plug for use with such a safety socket.

It is yet a further object of the present invention to provide a safety cover plate for connecting conventional sockets into a safety coupling.

A further object of the present invention is to provide a socket adapter for converting a conventional socket into a safety socket. I

Yet another object of the present invention is to provide a safety socket-and-plug arrangement whereby the power-supplyline attached to the socket becomes auwhen it is indispensable that one electric circuit be con-,

nected only to one other electric circuit with exclusion of any possibility of establishing an erroneous connection (e.g. from a loudspeaker system to a 220-V. supply network). In addition, it isalso convenient for certain applications (household as well as industry) to automatically disconnect an outlet socket from the supply line to which it is coupled when its corresponding plug is withdrawn whereby the contacts of the socket do not remain alive.

Accordingly, it is the object of the present invention to provide a protective coupling for establishing an electric connection between two electric circuits, ,or two branches of an electric circuit, or between a power-supply network and an electric power-consuming device or load, which does not suffer from the disadtomatically disconnected from the externally accessible contacts of the vsocket when the plug is withdrawn therefrom.

A still further object of the present invention is to provide a safety socket-and-plug arrangement wherein access to the connectors of the socket is prevented upon the plug being withdrawn from the socket.

Still another object of the present invention is to provide a safety socket-and-plug arrangement wherein no adverse effects are caused by any contact between the vide a polarity-selective safety socket-and-plug arrangement.

One of the two complementary couplers of my improved coupling, specifically the socket, is provided in the usual manner with at least one concealed first electrical (female) connector matingly engageable by a second (male) connector on the other coupler i.e., the plug, through an access opening whenever the two couplers are operatively interengaged; the female connector is energizable from a power supply whereas the male connector is adapted to be tied to a load as is well known per se. However, energization ofan extraneous object other than the associated male connector, introduced through the access opening into contact with the female connector, is prevented by safety means j through the brotepctiv'e equaling shown a with 'thefplug spaced fromihe socket;

effect such energization is inhibited, accordingtola fete ture of my invention, by a mechaniemforming part of thefaforementioned safety ;;means. The, two magnetic x mean'sare preferably anao'tiye element(magrtetfon More specifically; theengagemen-vtnhtbiting mecha C' the'access opening, for jswing ingjin a planeparallel thereto; l

Alternatively, the" oeket may (remain a I carrierfforf' the female connectorwhich has an extension'norm ally epaced from a supply terminal in the'hou ing, thetcafi 'rierbeing movable jointly withtheplng fm'm thls nor 1 mal position into an alternate positionupon releaserofy F "detentmeans by magnetic iHIQXFiIQ tlOH Of' the two afore- 3 rr'nentibried magnetic elementsfas the plug engages the socketfthis movement of thefpl'u'g jointly withthe cart a piyotal, motion, effeetive'ly corn-' r ier, which may [pletes the interengagementjoperationt;

U The aforedes cribed safety means may beeinclu'ded in an adapter for a Socket rather than in the socket"itself I the'adapte'r; being pro idedawith retaining=meane-flforf preventing'its detachment from the socket According t'o another embodiment of my invention,-l 7 ,the'coacting first ahdsebond-magnefi; means, on the v twioCcotrple'rs Jeaase jthehdisplacement 9f a' circuit piece upon the supply terminal and the associated con- 7 inector' extension, therebymaking that contactpressare j independent of the strength ofth'e coasting magnetic elements! f amanoescmrrionoerat; DRAWING If The above and other feataresflof my .inyention wills now be described in detail with referenceto the flQCOl'll-r' partying drawing'inwhichzt'l" l V V FIG J'I is a perspective view of one embodiment of a protective coupling c omprisirlg fa safety sbck'et and V breaker; vsu ch as a piston "within thehousing of the r "socket to complete a' working eircuit front aaupplyter-g minalto theload via the mating connectors-byplacing abridge piece thereon in c ontact wi ththat terminal and if with an extension'ofthefemale ConhectorhormalWin; V salated therefrom An ancillary circttitwithinythe socketpconiplet'ed at the Same tirne','includesrelectrm V magnetic rneans acting uponthe,cirCuitbreaker-in "a fsense qintensifying the contact pressure of thexbridge FIG: '2 isa rsc hematiegverttcal cross seotional view r,

FIG 3 isa sehem atic partial cross-sebtionalyview siln t flat-to that sh own inF 1G. 2 but representing a meaiaea ti on;

in FIG. ra t;

adapted to be deactivated, upon incipientfinterengage' u 'i mentgof the twofcotiplersi;by eoacting firstand second I I magnetic meanson the socket and on the plug respee- V tively, to, facilitate energi'zationof the loadvia the two 1; Q r mating cohnectors. Full]operative interenga'gementito j RG14ia aaehentatiejerplooetl bersbeeti veview afan advantageous embodimentof 'a'fisafety Fmrding! Q e' brese t invention FlG.,-5lis arisehematieekploded perspective View of a further embodimentof the presehtinvention;

I "FIG. Gjlaeherritzticexplodedperagieetive viewbf an' if additional embodiment;

' Fla s ieadiametral ems;

F1619 isa sehematie' shown in?Centrectionaprevehting' poeiti onil";

P104103 a' schematic illtistration',partiallyin-verti V i eajlcros ssectton, ofthe ernbodirnentiof BIG. 9but with Y 7 k if the pl gseen-inserted in thesocketanagwithyth qplest in connectiomes'tablfishingposition;fl

riththersocket in its/normal connection-preventing} coma tsaaanazeseeni e thereto;

2 Within were there isjrnorvabliy mamt a a magnetic 1 magnet, an eleetroma'gnet orabody of ferrornagneti e" ,paramagnetieor diamagheti'c mateirialiMagnetici'meme her 21 is mechanicallyuonneoted'by al link 21' toiaaup g portmember22 secured tofor irt'tegral with one end'of I Tan elastici'member 23,;w ho se otherend'ismourit 0n tia s upport vz ll rigi'd with l'plete lfl and "C1356 113. sup aa member-[22 made of electrically"insulating material y; I has moantedthereontwo,eontacts lfiylbwhichare movable therewithxContaCtsJZS; and; 2,6 face; fixed:

; lrco'ntae ts lfi andtrZ Q and are eonnectableljthereto.

The plugf associatedi with thisso'eketreomprises a t body 27 ofinsulatingmaterialgtowhichthere arelse-t l eured eleetrieally conductivegpins Z'S QZQ eXtendingr I outwardly, therefrom, onetfo'readh "fentaleleonnector j r V I m erf rj c' 14, 15 plug the latteri having beens howntin phantom lines;

: Theplng also incluglestnag n'etlernteanfill s ieam or integral "withbody preferably a permanent mag -,rf

connector ac;

FIG; yis'acliarnetral c roesr-vseetionalltview of the ernl 'boclimen't shown in FIGLfi vdth the afetyfs'qckefin; V

'onnec tionpreventi ngyp'osition and," he ping ready m a 1 be introduced intoithesock v 4 a ona ,view oftheemaf *bqdimmbf 6 u howmgy' herpm insenedinto thesoeket and with the latter ite eonnectiongenabling I position? V a x a lastra ti o'n;partia,llygin vertical;

cross-section,ofanothe embodiment Mm improved i I coupling wherein the blag has been shownready ta be l I inserted into the s'jo ck'et while 'f thefjaockethas been y I Sitionflgand FIGQIS ts aeschentatieexploded perspective vliewof 1 a I 'yetafarther embodime ntthe,breaent inyentiont v 3 In FIGS 1 'to'3,fI have showntwgo complementary. U couplers'gieg an electrie wallsoeketiandfa c'omplernentary plug. The*sockef includes a bodyfwlthaiface or eoyer'plate lflihalving two-bpe'nings'll, 12 extending therethrotighifPlate}fljislseeured byfsuitable meane to k y a case 13'"withinwhich therefaremounted,two fernale I connector membersf' 14, 15 I eleetrtbally extendedg through theback po r-tiqfi 1o ofrcae l3t 'bfygmeansuq f a v, 'pair of screws 17, 18iwhesepouter ncl hat/game" cts 25 i1fldi26 are conneetablego afirstelectric i circait while pins 28'and'29' are conneetable by means J V of wires 39 to aqseconaelectrie-cirettit. Mere partieur 4 larlymohtacts and-26 are conneetablef toranelectrie power-supply network while pins 28 and 29 are connectable to an electric power-consuming device or load.

The socket and plug described are interengageable by relative movement one toward the other.

If a permanent magnet 31 is mounted within the plug and member 21 is a permanent magnet or is of ferromagnetic material, insertion of the plug into the socket by such relative movement establishes an electric connection between the electric power-supply network connected to contacts 25 and 26 and the load con nected to wires 30. Such connection is caused by the attraction between complementary magnetic means 31 and 21 which cause contacts 25 and 26 to move into engagement with fixed contacts and 19.

Obviously, if the position of circuit breaker 19, 20, 25, 26 is reversed as shown in FIG. 3, it is necessary to invert the relative polarities of magnetic elements 21 and 31 so as to cause repulsion instead of attraction therebetween in order to connect mobile contacts and 26 with fixed contacts 20 and 19.

If elements 21, 31 were designed as two U-shaped permanent magnets (one in the plug and one in the socket), an electric connection between the power supply and the load could be completed only if the plug were inserted in the socket in a predetermined relative position, inasmuch as in any other position the magnetic interaction between elements 21 and 31 would not cause contacts 25 and 26 to approach contacts 19 and 20.

In order to indicate the correct relative position between the plug and the socket required'for closing the electric circuit, the former could be, for example, of nonsymmetric configuration or the diameter of pin 28 could be made substantially different from the diameter of pin 29.

It will be seen from the foregoing that if contacts 25 and 26 are connected toa power-supply network, the 7 insertion of any extraneous electrically conducting object such as a hair pin, a needle, etc. into the socket through openings or 12 and into contact with female connector members 14 and 15 will not cause the person inserting such object to receive an electric shock inasmuch as jack 14, screw 17, fixedcontact 20 and jack 15, screw 18 and fixed contact 19 are not alive, i.e. not connected to the power supply. However, if it is the plug shown that approaches the socket, contacts 25 and 26 are moved into engagement with fixed contacts 20 and 19, thereby closing the electrical circuit.

The socket of this embodiment, as well as in an inert atmosphere so as to avoid any problems derived from the formation of sparks .or arcs.

The elastic properties of contact carrier 23 assure that mobile contacts 25 and 26 become disconnected from fixed contacts 20 and 19 when the plug is withdrawn from the socket. This elastic member can obvi-' 'ously be replaced by any other means providing the tween the plug and the socket is eliminated, inasmuch that of other embodiments, could be encapsulated, if desired,

,i.e. a wall socket 50 and a plug 51. The socket 50 comprises a body 52 having unilaterally mounted therein two female connector members (not shown) accessible from the front of body 52 through perforations 53 and 54 and connectable to an electric power supply which has been schematically represented by wiresSS and 56. The socket described can be of any conventional type. On body 52 there is mounted a safety plate 57 freely rotatable around a pivot pin 58 which extends through an orifice in safety plate 57 and is held by bodySZ. Safety plate 57 has two perforations 59 and 60 which are aligned with its geometric axis of rotation (i.e. the axis of mounting pin 58) and are equidistant therefrom.

Mounting pin 58 is secured to body 52 at a location i which is also equidistant from perforations 53 and S4 and aligned therewith.

Safety plate 57 has two permanent magnets 61 and 62 secured thereto and is biased by a counterweight 63 into a position in which perforations 59 and 60 are not aligned with perforations 53 and 54. The magnetic axes of permanent magnets 61 and 62 are aligned with perforations 59 and 60. However, different relative positions are possible without departing from the spirit and scope of the present invention. Safety plate 57 may itself be of magnetic material with poles suitably positioned so that it would not be necessary to have separate magnets 61 and 62 mounted thereon. Also, counterweight 63 can be replaced by other biasing means such as a spring having the same effect.

Plug 51 includes a pair of male connector members or pins 64, spaced apart a distance equal to the spacing between perforations 53 and 54 and between perforations 59 and 60. The pins 64, 65 are electrically insulated from plug 51 and internally connected to a pair of wires 66. The free ends of connector members 64 and 65 have permanent magnets 68 and 69 mounted thereon.

The arrangement further comprises a face or covering plate 67 provided with perforations which in its wall-mounted position register with perforations 53 and 54 so as to permit the insertion of male connector members 64 and 65 into perforations 53 and 54 of socket 50.

In the position shown in FIG. 4, and with safety plate 57 movably mounted on body 42, safety plate 57 will normally adopt a position in which perforations 59 and r 60 are not aligned with perforations 53 and 54. In such a position, if it is attempted to introduce an electrically conductive extraneous object such as a hair pin into perforations 53 or 54 through the corresponding perforationsin face plate 67, safety plate 57 will prevent such extraneous object from entering into body 52 whereby it is impossible to establish an electric connec-' tion between the electric circuit,(wires 55, 56) associated with socket 50 and such object. However, by means of plug 51. which incorporates the means necessary to rotate safety plate 57 (for example through it is possible to interconnect the conductors 55', 56, and 66. This rotation is caused by complementary magnetic means 61, 62, 68 and 69 which cause safety plate 57 to rotate when pins 64 and 65 commencepenetrating the perforations in covering plate 67 whereby the fields of permanent magnets 68 and 69 and of per-.

. plate 67. V

From the foregoing, it will be evident that safety plate 'nent magnet;

manent magnets 61 and 62 interact until perforations l 59 and 60 coincide with perforations 53 and 54. The

end positions of safety means57 can, if desired, be dc termined by meansof abutments (not shown) present, for example, on body 52 and/or on the inner face of 57 is movable with respect to body 52 between-a first position preventing any electric connection from being I established between the electric circuit associated with socket 50 and an extraneous object, and a second'position enabling the establishment of an electric connection between supply wires 55, 56 and a load connected to wires 66. V

Naturally, the number of perforationsrequired in the safety plate 57 of FIG. 4 depends on the. number of pairs of mating connectors in socket 50 and plug 51. Furthermore safety plate 57 could also incorporate in place of permanent magnets61 and 62 two passive bodies of paramagnetic or diarnagnetic material so .that, upon insertion of plug 51 (withmagnets 68 and 69) through theperforations in plate 67, the magnets 68 and 69 swillca'use movement of these bodies, thereby rotating safety plate57 and enabling the estab lishment of an electric circuit.

Although, by way of example,it has been stated that safety plate 57 rotates through 90, it is obvious that by repulsion so as to avoid the possibility of an object of ferromagnetic material being insertedinto perforations 53and 54 by virtueof the interaction of magnets V 74 and 75 with the ferromagnetic material of the extraneous object. A further way to avoid this problem is that magnetic elements 74, 75 simply be-two passive I bodies of ferromagnetic, paramagnetic or diamagnetic 7 mechanically connected ,by means of brackets 72 and.

73 to the magnetic means 74, 75butcould1alsobe intematerial, and magnetic elements 68, 69 be permanent magnets. I Itisevident that safety plates 70 and 71 need not be grated therewith. V

. With the scope of the embodiment shown in FIG- itwould also be possible to provide a plugSl incorporating two conventional pins and a third pin, connectestablishmentof an electric contact betweengthesocket 7 any other extent of rotation is acceptable as long as 7 and the plug when one is moved toward the other;

plate 57 in its normal position blocks access tobody 52 I and in its alternate position'givesaccess theretopThe angle of rotation of safety plate 57 can, be varied, for

example, by modifying the relative pos'ition'of magnetic I be mounted 'on the front face'of socket 50. However, it is obvious that, if desiredjsafety plate 57' could also be mounted within body 52 or even on theinner face of covering plate 67.

means 61 and 62 with respect to perforations S9 and In FIG. 5 a. further embodiment is shown'which is I used to designate identical or equivalent parts.

The basic difference between the two embodiments 1 similar to the embodiment represented in FICi. 4 and wherein corresponding reference numerals have been" is'that safety plate 57 with its perforations, magnets and I 7 counterweight has been replacedin FIG. Sbyapair of plates 70, 71, pivoted with respectto body/'52 and normallyina position'covering' perforations 5 3 and 54.

Each plate and 71; isjconnecte'dbymeansiofiaN bracket 72 and 73, respectively to an associatedmag netic element 74, 75.preferably consisting of a permaw i By means of this arran frustrated by safety plates 70.0'r 71. However, inorder genient, ifanyone were to at-= tempt to insert an extraneous objectinto perforations 53 or 54, which provide access to the contact or con- .nector members. of socket 50 suchfatteimpt would be able to ground, with a magnet arranged at its free end. In this case, its corresponding socket would require three perforations, two of which (the conventional. ones) would be normallyblocked by safety plates 70,

7 1 while the third perforation would be free so as to enable the insertion of the grounded third pin of plug 51. Inthis case, a single magnet arranged onthefreeiend l of the third or ground pinof plugSl would serve to" move (preferably by repulsion) magnets 74 and 75 along with safety plates 70 and 71, thereby enabling the The third pin'would thenbecorne connected to a nor-, mally grounded thirdcontact or connector member in' socket 50.:

In'practice, it

plates (seeFIGS.'4and5)it is possible, althoughvery difficult, to cause the rotation of safety plate 57,70 or 71 by inserting, for example a screwdriver through the perforations oraccessyholes incovering plate-"67 and it wiggling its flat end resting against thesafety plate In order toavoid such a possibility,l prefer to incorporate in safety plate v57 or plates 7(land 7i additionalsafe guards for preventing such exteriorly caused movement of the safety platetowardsjits connectiomenabling position. Such safeguards; may comprise; a recessYS," aligned with these access holes as seen, in FIG. 4,

whereby it is virtually irnpossible to move safety plate 57 byinserting, for example, a screwdriver androtating I it around a, geometric axis" variablyfinclined with 're- V specttoa perpendicular to safety plateifi'i or 70 or 71.

This saineeffect could "be obtained by other. means.

, such as, for example, two straps secured in spaced rela-, tionship-over safety'plate 57hr platesflthcor 7 l, and; def

fining a channeltherebetweenaligne djwith the perforations'i-n covering'plate 67 when these platesareain their connectiompreventing positions;

,ln theembodimentsssotfar described, the'operation i of connecting a powensupply network,.'or a first elec-, I tric circuit, to a load, or a second electriccircuit,is car ried out by a single mechanical operation inasmuch as v the conditioningxof the socketfloccursautomatically. upon the manual interengagement of the two comple- :mentary devices, l I

Certain embodimentswill now be described in which the usernmust perforrnthese operations intwo succes-w 'sive steps.

in this context l shall now referto FIGS. 6,? a d s I g whereinamsockebandplugarrangement W0, it)! has V f been shown. Theisocket comprises a body 102 has been foundlthatin allth'e embodii ments of the present inventionincorporatingsafety which has mounted thereon two stationary contacts or prongs 103, 104, insulated from each other and from that body. Contacts 103 and 104 are connectable to an electric circuit, such as a power-supply network, and may therefore be described as supply terminals. Body 102 has a first protruding crown-shaped portion or serrated annular boss 112 integral therewith. Socket 100 also comprises an intermediate carrier member 105 rotatably mounted with respect to body 102. Intermediate member 105 comprises a first cylindrical portion or sleeve 106 having two external prongs or contacts 107, 108 mounted thereon and a second hollow cylindrical portion or sleeve 109 carrying therein two conductor members 110, 111 each electrically connected to a respective prong 107, 108 serving as an extension thereof. A second protruding crown-shaped member or serrated annular boss 113 is axially slidable with respect to member 105, although barred from any rotational movement with respect thereto by means for example, of a keyed or splined mounting (not shown).

Boss 113 has magnetic means in the shape of a magnetic pin 114 integral therewith and extending into sleeve 109 through a perforation in sleeve 106.

Although intermediate member 105 is rotatable with respect to body 102, prongs 103 and 104 can be brought into electric contact with prongs 107 and 108 only when the serrated bosses or detents 112 and 113 are in the axially separated positions shown in FIG. 8; if they are closely juxtaposed as shown in FIG. 7, intermediate .member 105 is prevented from rotating with respect to body 102 by the engagement of their serrations and by the nonrotatable mounting of pin 114 with respect to intermediate member 105.

Plug 101 comprises a substantially cylindrical portion or stem 115 having two diametrically opposite flattened faces (only one shown) carrying conductor members 116 adapted to establish conductor with contact members 110 and 111 upon plug 101 being inserted into sleeve 109. The terminals of plug 101 are electrically connected to wires 117 connectable to a load circuit such as an electric appliance. Within stem 115 of plug 101 there is mounted a magnetic element such as a permanent magnet 118 adapted to cooperate, upon insertion of plug 101 into intermediate member 105, with magnetic pin 114. Preferably, pin 114 is a permanent magnet, although for example a passive body of paramagnetic material will also be suitable. Obviously, pin 114 does not necessarily have to be made in its entirety of magnetic material as it is sufficient that the end thereof remote from boss 113 have magnetic character. By means of the components described with reference to FIGS. 6 and 8, there is provided a safety arrangement adapted to operate as follows:

With prongs 103, 104 of socket 100 permanently connected to an electric power supply, if itis desired to energize the wires 117 it is necessary to insert plug 101, and more particularly cylindrical stem 115 thereof. into the cylindrical sleeve 109 of socket 100. In this way. conductors 116 of plug 101 come into conductor with contact members 110 and 111, which in turn are connected to contacts 107 and 108. In the normal, connection-preventing position of plug 100, contacts 107 and 108 are angularly offset from contacts 103 and 104. Unless it is plug 101 that is inserted into socket 100, it is not possible to rotate intermediate member 105. However, if plug 101 is so inserted, magnetic element 118 attracts magnetic element 114 to disengage the serrated boss 112 from the coacting boss 113 and allow the intermediate member 105 to be manually rotated with respect to body 102, whereby movable prongs 107 and 108 come into electric contact with stationary prongs 103 and 104 as has been shown in FIG. 8.

In the event that an extraneous object is placed in 2 contact with conductors 110 and 111, no damage can be caused inasmuch as these conductors are not normally connected to the electric power supply. Moreover, it is normally impossible to rotate, by using extraneous means, intermediate member 105 with the aim of placing prongs 107, 108 in contact with prongs 103, 104, inasmuch as much extraneous means would not disengage the two bosses 112, 113 from each other.

Obviously, means are provided, such as a spring (not shown), to return the boss 113 to its engaging position with the boss portion 112 upon plug 101 being withdrawn from socket 100. Similarly, means are also provided to enable plug 101 only to be withdrawn from socket when prongs 107 and 108 are free from electric contact with prongs 103 and 104.

From the foregoing, it will be seen that boss 113 and magnetic pin 114 (safety means) have a normal first position preventing the establishment of an electric connection between the electric circuit associated with socket 100 and an extraneous object, and are movable to a second position enabling the establishment of an electric connection between the power supply network connected to socket 100 and the load connected to plug 101.

Thus, in the embodiment of FIGS. 6, 7, and 8 the operations which must be performed are first the insertion of the plug into the socket (whereby the socket is conditioned to allow the electric connection to be established) and then a predetermined manipulation for mechanically establishing the required connection.

Reference will now be made to FIGS. 9 to 11 which show a further embodiment of my invention.

In accordance with this embodiment, the socket comprises a body or housing 200 having mounted therein two stationary contacts 201 (the other one is not seen in this Figure) insulated from each other and from body 200. Body 200 is internally formed with an abutment 200. Swingable about a pivot pin 203 within body 200 is a carrier member 204 having two contacts 205 (only one being visible) mounted thereon and arranged so that upon member 204 rotating in a clockwise direction about pivot point 203, contacts 205 come into engagement with contacts 201. Contacts 201 are connectable to an electric circuit (not shown), such as an electric power supply, by means of conductors 201.

Member 204 is hollow and its inner end defines an opening through which there extends a plunger 206 of magnetic material having an enlarged head positioned within member 204 to prevent its disengagement therefrom. The other end of member 204 is open and accessible from the outside. Normally, magnetic member 206, which constitutes a detent forming part of the safety means of this embodiment, projects from member 204 and because of its engagement with abutment 202 prevents the rotation of member 204 and thereby the possibility of any circuit closure between movable contacts 205 and stationary contacts 201.

Body 200 includes a curved front plate 207 provided with a vertical slot, while member 204 carries a shield 208 which is slidable relative to curved plate 207 on the inner face thereof. Shield 208 has an opening coextensive with the opening of member 204, providing access thereto from outside.

The arrangement comprises a complementary plug 209 engageable with the socket just described.

Plug 209 comprises a prismatic stern 210.capable of being inserted into the correspondingly shaped hollow portion of member 204 through curved plate 207 and shield 208. The plug has a shoulder 211 and a knob 212. The shoulder 211 serves to limit the inward movement of plug 209 into member 204.

Plug 209 is electrically connectable to an electric load circuit by means of wires 213 each connected to one of two conductors 214 positioned on opposite faces of stem 210. With this arrangementgupon plug 209 being inserted into the socket, conductors 214, 214 come into engagement with a corresponding contact 205.

In addition, plug 209 has at its free end magnetic means 215, for example, a permanent magnet, which, upon plug 209 being inserted into the socket, will attract the plunger 206, thereby carrying it to a releasing position, enabling the establishment of a connection between contacts 205 and 201, by rotation of member 204 in a clockwise direction as shown by arrow 216. Such rotation must be effected by the user by pressing downwardly on knob 212.

In order to prevent plug 209 from being withdrawn when the arrangement is in the operating position shown in FIG. 10, channel-shaped recesses 217 are provided which engage the sides of the vertical slot defined in curved plate or front wall '207 which thus acts as a locking means for the plug. This vertical slot has an enlarged portion at its upper end through which plug 209 can be inserted and withdrawn from the socket. In this way, plug 209 can be withdrawn only when member 204 is in the normal or blocking position shown in FIG. 9, being otherwise held in place by the constricted slot portion. Similarly, plug 209 can be inserted into its corresponding socket only when the socket is in the position shown in FIG. 9. It will be seen that upon inserting an extraneous object into the socket positioned as shown in FIG. 9 and more particularly into member 204, such extraneous object, even if it should come into contact with contacts 205, will not be electrically connected to the power supply inasmuch as their downward extensions are not in engagement with supply terminals 201. Similarly, it is impossible to cause rotation of member 204 by means of such an extraneous object, in view of the interlocking between magnetic member 206 and abutment 202. It will accordingly be seen that the normal position shown in FIG. 9 prevents the establishment of any electric connection between the electric circuit associated with the socket and an extraneous object, whereas upon a forward shift of magnetic member 206 within member 204 (off-normal position) it is possible to establish an electric connection between, for example, a power supply and a load, connected to wires 213, by swinging the member 204 about its pivotal axis.

Obviously, when member 204 is in the upwardly inclined position shown in FIG. 9 and the plug is not inserted thereinto, the magnetic plunger 206 will be driven by gravity into locking engagement with abutment 202. If additional safeguards are needed, plunger I 206 could be placed under the effect of a biasing spring tending to move it rearwardly toward its blocking position. Both the effect of this spring as well as the effect of gravity are overcome by the magnetic attraction existing between plunger 206 and magnetic means 215 upon the plug being inserted into member 204.

Advantageously, plunger 206 should not be designed the exertion of considerable contact pressure between a movable: contact and a stationary contact.

In the embodiment of FIG. 12, the socket comprises a hollow body or housing 300 of insulating material which has mounted therein a pair of supply terminals 301, 301' connected to a power source schematically represented by arrows 302. Body 300 defines two perforations 303, 304 lined at least in part by electrically conductive bushings 305, 306. These busings 305, 306

are electrically connected to contacts 307, 308 serving as extensions thereof. Within body 300 there is slidably mounted a circuit breaker in the form of a nonconductive piston member 309 having bridge pieces 310, 311 mounted thereon. These bridge pieces 310, 311 are arranged in such a way that, upon member 309 sliding toward the right (as viewed in FIG. 12), bridge piece 310 interconnects the contacts 301 and 307 while bridge piece 311 interconnects the contacts 301 and 308, whereby an electric connection is established between power source 302 and conductive bushings 305, 306.

In addition, member 309 carries magnets 312, 313 substantially aligned with perforations 303, 304. Member 309 is secured to a movable coil 314 of an electromagnetic device Whose armature 314' is secured to body 300. Armature 314' is a suitably oriented permanent magnet so polarized as to cause member 309 to move to the right upon energization of coil 314. Coil 314 is permanently connected (in an ancillary circuit schematically represented by wires 315) to tabs 322, 323 of jacks or bushings 305, 306. Piston member 309 is normally biased toward its retracted or connectionpreventing position (i.e., the position shown in FIG. 12) by springs 316.

The arrangement further comprises a plug 317 which is conventional in most aspects except that the free ends of pins 318, 319 incorporate permanent magnets 320,321. If desired, these magnets 320, 321 could be replaced by a single permanent magnet in the body of the plug as shown, for example, in the embodiment of FIG. 2; obviously it would then be necessary to slightly modify the positioning ofmagnets 312, 313.

Upon inserting pins 318, 319 of plug 317 into perforations 303 and 304, the mutual attraction of magnets 320, 321,312, 313 draws the piston 309 to the right (as viewed in FIG. 12), whereby bridge pieces 310, 311 will interconnect contacts 301 and 307 as well as contacts 301' and 308. Upon the supply leads 302, 302' becoming connected to contacts 322 and 323, electromagnet 314 will be energized, thereby intensifying the contact pressure between contacts 301', 307 and If an extraneous object were to be inserted into perforations 303, 304, it would be most difficult for such an object to reach the contacts 301, 301 inasmuch as the latter are hidden and inaccessible from outside.

It will be obvious to those skilled in the art that the present invention is not limited to incorporating safety means into the combination of a plug with a socket or a cover plate therefor, inasmuch as it is also possible to incorporate the novel features of any of the sockets described and claimed into an adapter capable of converting a conventional socket into a protected one. In this case the adapter may be semi-permanently connectable to a conventional socket. Thishas been shown in FIG. 13 where reference 400 designates a conventional wall socket while reference 401 denotes an adapter in accordance with the present invention. The

adapter 401 comprises two pins 402 insertable into perforations 403 of the convention socket 400. Adapter 401 has internal conductors electrically connected one to each pin 402 and accessible from outside through perforations 405 and 406. In addition, adapter member 401 incorporates magnetically controlled safety means in accordance with'any of the preceding embodiments, preferably those of FIGS. 1 to 5.

In order to avoid the risk of adapter socket 401 being withdrawn from conventional socket 400, once it has been inserted thereinto, retaining means,404 are provided which, for example, can comprise a pair of elastic blades 404 mounted at the ends of pins 402 and which, once pins 402 have been inserted into perforations 403, prevent the adapter 401 from being withdrawn. Obviously, the particular construction of retaining means 404 is not an important aspect of the present invention and a large number of different structures can be conceived to the same end.

It will be understood that the embodiments described by way of example aresusceptible of modifications as to their construction and materials without departing from the scope of the invention as specifically defined in the following claims.

I claim:

1. A protective electric coupling comprising:

a first coupler provided with at least one concealed first electrical connector adapted to be tied to a source of electrical energy;

a second coupler complementary to said first coupler provided with a second electrical connector adapted to be tied to a load, said second connector being matingly engageable with said first connector through an access opening in said first coupler upon operative interengagement of said couplers;

safety means in said first coupler for preventing the energization of an extraneous object other than said second connector introduced through said access opening into contact with said first connector; and

coacting first and second magnetic first and second couplers for deactivating said safety means upon incipient interengagement of said couplers to facilitate energization of the load via said connectors, said safety means including mechanism effective prior to deactivation thereof for inhibiting full operative interengagement of said couplers.

means on said 2. A protective electric coupling as defined in claim 1 wherein said first and second magnetic means comprises a passive magnetic element on said first coupler and an active magnet on said second coupler.

3. A protective electric coupling as defined in claim 1 wherein said first and second magnetic means are a pair of magnets polarized to repel each other;

4. A protective electric coupling as defined in claim 1 wherein said mechanism comprises a blocking member normally obstructing said first connector and carrying said first magnetic means, said blocking member being deflectable into a nonobstructing position by magnetic interaction of said first and second magnetic means.

5. A protective electric coupling as defined in claim 4 wherein said second magnetic means is mounted on said second connector for introduction into said access opening.

6. A protective electric coupling as defined in claim 4 wherein said first coupler includes a front plate provided with said access opening, said blocking member being swingable behind said front plate in a plane parallel thereto.

7. A protective electric coupling as defined in claim 6 wherein said blocking member is provided with a depression normally in line with said access opening for preventing a displacement of said blocking member by a tool inserted therethrough.

8. An adapter for a socket provided with a jack connected to a source of electrical energy and engageable by a pin of a plug connected to a load, comprising a body, a male connector extending from said body for insertion into said jack, afemale connector on said body adapted to receive said pin, circuitry in said body for extending an electricalconnection from said jack through said connectors and said pin to the load upon operative interengagement of said plug with said body, safety means in said body for preventing the energization of an extraneous object other than said pin introduced into said female connector, magnetic means in said body displaceable by a magnet on said plug for deactivating said safety means upon incipient interengagement of said plug with said body, said safety means including mechanism effective prior to deactivation thereof for inhibiting full operative interengagement of said plug and said body, and retaining means on said body for preventing its detachment from a socket engaged thereby.

9. A wall socket having a body provided with an access opening and a concealed electrical connector contactable through said access opening by a mating pin of an associated plug and adapted to be tied to a source of electrical energy, said socket comprising:

a blocking member between said access opening and said connector for normally obstructing the latter to prevent energization of an extraneous object other than said pin inserted into said access opening; and

magnetic means on said blocking member positioned to interact with a magnet on said plug upon incipient penetration of said access opening by said pin to displace said blocking member into anonobstructing position. 

1. A protective electric coupling comprising: a first coupler provided with at least one concealed first electrical connector adapted to be tied to a source of electrical energy; a second coupler complementary to said first coupler provided with a second electrical connector adapted to be tied to a load, said second connector being matingly engageable with said first connector through an access opening in said first coupler upon operative interengagement of said couplers; safety means in said first coupler for preventing the energization of an extraneous object other than said second connector introduced through said access opening into contact with said first connector; and coacting first and second magnetic means on said first and second couplers for deactivating said safety means upon incipient interengagement of said couplers to facilitate energization of the load via said connectors, said safety means including mechanism effective prior to deactivation thereof for inhibiting full operative interengagement of said couplers.
 2. A protective electric coupling as defined in claim 1 wherein said first and second magnetic means comprises a passive magnetic element on said first coupler and an active magnet on said second coupler.
 3. A protective electric coupling as defined in claim 1 wherein said first and second magnetic means are a pair of magnets polarized to repel each other.
 4. A protective electric coupling as defined in claim 1 wherein said mechanism comprises a blocking member normally obstructing said first connector and carrying said first magnetic means, said blocking member being deflectable into a nonobstructing position by magnetic interaction of said first and second magnetic means.
 5. A protective electric coupling as defined in claim 4 wherein said second magnetic means is mounted on said second connector for introduction into said access opening.
 6. A protective electric coupling as defined in claim 4 wherein said first coupler includes a front plate provided with said access opening, said blocking member being swingable behind said front plate in a plane parallel thereto.
 7. A protective electric coupling as defined in claim 6 wherein said blocking member is provided with a depression normally in line with said access opening for preventing a displacement of said blocking member by a tool inserted therethrough.
 8. An adapter for a socket provided with a jack connected to a source of electrical energy and engageable by a pin of a plug connected to a load, comprising a body, a male connector extending from said body for insertion into said jack, a female connector on said body adapted to receive said pin, circuitry in said body for extending an electrical connection from said jack through said connectors and said pin to the load upon operative interengagement of said plug with said body, safety means in said body for preventing the energization of an extraneous object other than said pin introduced into said female connector, magnetic means in said body displaceable by a magnet on said plug for deactivating said safety means upon incipient interengagement of said plug with said body, said safety means including mechanism effective prior to deactivation thereof for inhibiting full operative interengagement of said plug and said body, and retaining means on said body for preventing its detachment from a socket engaged thereby.
 9. A wall socket having a body provided with an access opening and a concealed electrical connector contactable through said access opening by a mating pin of an associated plug and adapted to be tied to a source of electrical energy, said socket comprising: a blocking member between said access opening and said connector for normally obstructing the latter to prevent energization of an extraneous object other than said pin inserted into said access opening; and magnetic means on said blocking member positioned to interact with a magnet on said plug upon incipient penetration of said access opening by said pin to displace said blocking member into a nonobstructing position. 